Food Chains, Food Webs, and the Transfer

of EnergySymbiosis and Succession

too!

Autotrophs

• A groups of organisms that can use the energy in sunlight to convert water and carbon dioxide into Glucose (food)

• Autotrophs are also called Producers because they produce all of the food that heterotrophs use

• Without autotrophs, there would be no life on this planet

• Ex. Plants and Algae

Autotrophs

Autotrophs

• Chemotrophs– Autotrophs that get their energy from

inorganic substances, such as salt– Live deep down in the ocean where there is

no sunlight– Ex. Bacteria and Deep Sea Worms

Heterotrophs

• Organisms that do not make their own food

• Another term for Heterotroph is consumer because they consume other organisms in order to live

• Ex. Rabbits, Deer, Mushrooms

Heterotrophs

Heterotrophs

• Consumers– 1. Scavengers/Detritivores – feed on the

tissue of dead organisms (both plans and animals)

• Ex. – Vultures, Crows, and Shrimp

Heterotrophs

• Consumers– 2. Herbivores – eat ONLY plants

• Ex. – Cows, Elephants, Giraffes

Heterotrophs

• Consumers– 3. Carnivores – eat ONLY meat

• Ex. – Lions, Tigers, Sharks

Heterotrophs

• Consumers– 4. Omnivores – eat BOTH plants and

animals • Ex. – Bears and Humans

Heterotrophs

• Consumers– 5. Decomposers – absorb any dead

material and break it down into simple nutrients or fertilizers

• Ex. – Bacteria and Mushrooms

Transfer of Energy

• When a zebra eats the grass, it does not obtain all of the energy the grass has (much of it is not eaten)

• When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)

Transfer of Energy

• The two (2) previous examples of energy transfer show that no organism EVER receives all of the energy from the organism they just ate

• Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law

Trophic Levels

• Energy moves from one organisms to another when it is eaten

• Each step in this transfer of energy is know as a trophic level– The main trophic levels are producers,

consumers, and decomposers

Food Chains• The energy flow from one trophic level to the

other is know as a food chain• A food chain is simple and direct• It involves one organism at each trophic level

– Primary Consumers – eat autotrophs (producers)– Secondary Consumers – eat the primary consumers– Tertiary Consumers – eat the secondary consumers– Decomposers – bacteria and fungi that break down

dead organisms and recycle the material back into the environment

Food Chain

Food Web

• Most organisms eat more than JUST one organism

• When more organisms are involved it is known as a FOOD WEB

• Food webs are more complex and involve lots of organisms

Food Web

Food Web

• Notice that the arrow points in the direction of the energy transfer, NOT “what ate what”

Food Web

Biomass

• The total mass of the organic matter at each trophic level is called biomass

• Biomass is just another term for potential energy – energy that is to be eaten and used.

• The transfer of energy from one level to another is very inefficient (10% Law)

Biomass

Ecological Pyramid

• An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem

• Shows the relative amounts of energy or matter contained at each trophic level

• The Pyramid shows which level has the most energy and the highest number of organisms

Ecological Pyramid

Ecological Pyramid

Ecological Pyramid

• Which level has the most energy?• Which level has the most organisms?• Which level has the least organisms?• Which level has the least energy?

Symbiosis

• A close and permanent association between organisms of different species– Mutualism – a relationship in which both

organisms benefit from each other• Example: Birds eating pest off a rhino’s back

– Commensalism – a relationship in which one organism benefits and the other is not affected

• Example: Barnacles on a whale

– Parasitism – A relationship in which one organism benefits and the other is harmed

• Example: Ticks on a dog

In your Lab notebook complete the following:

Symbiotic Relationship

Textbook Definition

My definition (less than 4 words)

My example

Commensalism

a relationship in which one organism benefits and the other is not affected

Mutualism a relationship in which both organisms benefit from each other

Parasitism A relationship in which one organism benefits and the other is harmed

Ecological Succession: Some Definitions

• the gradual and directional process of species change in a community

• biotic communities change through time in response to many influences: – climatic change – disturbances – invasion of species from other areas

• Eventually, succession leads to a climax community

Primary Succession

• the processes and progress involved in changing an area from one lacking any community (no plants, no animals, no insects, no seeds, etc.) to one consisting of individuals, populations, communities, and ecosystems.

• the arrival of life in an area where no community previously existed.

Example of Primary Succession

Secondary Succession

• The arrival of new species in an area that already has life.

• Results in the transition of a community from pioneer species to climax species.

• Because soil may already be present, the rate of secondary succession is faster than primary succession.

• Secondary succession also indicates changes in community composition following disturbances.

Example of Secondary Succession

This is an example of a

secondary succession following a disturbance

(fire). It does not

completely wipe out life.

What is a Pioneer Species?

•The first species to colonize an area (usually lichens and mosses but sometimes higher plants), beginning the process of soil formation.

What is Climax Community?

A community that remains fairly constant in species

composition if the land and climate are undisturbed.

These are the communities that characterize the various

biomes.

A summary of changes that occur during succession:

• Pioneer species colonize a bare or disturbed site. Soil building. • Changes in the physical environment occur (e.g., light, moisture). • New species of plants displace existing plants because their

seedlings are better able to become established in the changed environment.

• Newly arriving species alter the physical conditions, often in ways that enable other species to become established.

• Animals come in with or after the plants they need to survive. • Eventually a climax community that is more or less stable will

become established and have the ability to reproduce itself. • Disturbances will start the process of succession again.

“Food Web of Biome_____”

this is your title1. Choose a Biome from

pg 99-104) to draw a food web

2. Draw, Color and Label your Food Web– Example on pg 71– A food web shows how

two or more food chains interact

3. Must show arrows showing energy flow– What eats what

4. Must label organisms as:– Method of nutrition

• Producer• Herbivore• Carnivore• Omnivore

– Tropic Level• Producer• 1st Consumer• 2nd Consumer• 3rd Consumer• Decomposer or Scavenger

•Don’t forget about the SUN!